need advice on tuning this query

I am trying to tune the following query 

SELECT RECM_GRP_CDE,
(CASE WHEN CHAN_CDE = 'AM' AND BUS_ORG_CDE in ('CS','MS') THEN 'IB'
      WHEN CHAN_CDE = 'IVR' THEN 'IVR'
      WHEN CHAN_CDE in('AM','EAM') AND BUS_ORG_CDE in ('EEX', 'MAX', 'ES', 'EN', 'RS', 'US', 'CSE') THEN 'CSE'
 END) CHAN_CDE,
LST_ACCPT_TMS, LST_DCLN_TMS, ACCPT_RSPNS_CNT, DCLN_RSPNS_CNT
FROM TABLE1 WHERE ACCT_NBR='12335' AND CUST_TYP_CDE in ('U','P') AND
(LST_ACCPT_TMS > to_date('19010101','yyyymmdd') OR LST_DCLN_TMS > to_date('19010101','yyyymmdd')) AND